To increase the recording density of a magnetic recording apparatus, a microwave assisted magnetic recording method is proposed. The microwave assisted magnetic recording method reduces the magnetic switching field of a magnetic recording layer on a magnetic recording medium by applying a high-frequency magnetic field to the magnetic recording medium. This can increase the recording density using a magnetic recording layer having high coercivity (Hc) and high magnetic anisotropy energy (Ku).
A technique using a spin torque oscillator as the source for generating such a high-frequency magnetic field is disclosed. The high-frequency magnetic field is generated from a field generation layer of the spin torque oscillator. To generate a high-intensity high-frequency magnetic field in order to improve the long-term reliability, it is preferable that the spin torque is efficiently applied to the field generation layer.